TECHNICAL ASSISTANCE PROGRAM
for the CALAIS, MAINE
WASTE WATER TREATMENT PLANT
U.S. Environmental Protection Agency
New England Regional Office, Boston, Mass.
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TECHNICAL ASSISTANCE PROGRAM
Calais, Maine
Hibbard E. Armour, P.E.
Chief, Operation and Maintenance Section
Air and Water Programs Division
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION I
John A. S. McGlennon
Regional Administrator
October 1974
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Abstract
The Calais, Maine, WWTP discharges to the St. Croix River,
an international waterway, and as such is of interest to the
International Joint Committee Advisory Board on the St. Croix.
The IJC reported operating problems at the Calais plant and an
investigation was initiated. This led to a full scale technical
assistance program conducted jointly by the Operations and
Maintenance staff of the Environmental Protection Agency, Region
I, and the Maine Department of Environmental Protection.
The findings of a field reconnaissance indicated that a
change in operating mode, from contact stabilization to plug
flow conventional activated sludge, was feasible. A formal
request for technical assistance was prepared by the City and
forwarded by the State to EPA Region I. In response to this,
the program was started on July 15, 1974. The mode of opera-
tion was changed and operating control measures, developed
by Mr. Alfred West, Chief, Waste Treatment Branch, National
Field Investigation Center, Cincinnati, Ohio, were put into
practice.
The program was hampered by problems associated with the
final clarifiers, the return sludge pumping rates, and mechanical
aerator controls, and most serious of all, chemical interferences
related to sludge dewatering. The clarifiers were temporarily
modified and the mechanical problems were coped with through
manipulation of controls. The chemical upsets were attributed
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to improper dosing of sludge during its conditioning for dewatering.
The corrections resulted in a marked improvement in plant operation.
The historical plant efficiency was established at 68 percent.
During the resident phase of the program, efficiency increased to
79 percent and during the second phase it increased to 91 percent.
The overall program is considered to be successful.
Acknowledgments
The relative success of the technical assistance program
at Calais was due to very excellent cooperation between EPA
Headquarters, the EPA Cincinnati NFIC, the Maine DEP, and
EPA Region I. The encouragement and technical advice from
Alfred West and Charles Bardonner of the Waste Treatment
Branch of the NFIC was most welcome and greatly appreciated.
Hibbard E. Armour, Chief of the Region I Operations and
Maintenance Section, and Dr. James Bryant from EPA Head-
quarters’ Municipal Operations Branch conducted the field
reconnaissance and participated during the first week of the
exercise. Larry Brill from the 0 & M Section controlled the
field operation, assisted by Kenneth Shirkey, Glen Foss, and
James Thornton from the Maine DEP.
None of the work could have been accomplished without the
cooperation of Darrell Elsemore, City Manager of Calais, and
the plant operating personnel, Douglas Moore, Robert Cole, and
Douglas Kelly.
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ENVIRONMENTAL PROTECTION AGENCY
REGION I
TECHNICAL ASSISTANCE PROGRAM
CALAIS, MAINE
Table of Contents
Page
Purpose 1
Calais Wastewater Treatment Plant 2
Plant Operational History 3
Field Reconnaissance 4
Preparation for Technical Assistance Program 6
Technical Assistance Implementation 8
Plant Responses
Clarifier Modifications 9
Return Sludge Pumping Control Measures 9
Chemical Interferences 10
Mechanical Aerator Operation 11
Outside Interferences 11
Evaluation of Program
Historical Background 13
Phase I 13
Phase II 15
Recomendations 16
Conclusion 19
Appendices
A - Historical Operational Data
B - Pertinent Data
C - Operational Variables
o - Staffing Requirements
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ENVIRONMENTAL PROTECTION AGENCY
REGION I
TECHNICAL ASSISTANCE PROGRAM
CALAIS, MAINE
Purpose
The City of Calais is located in Washington County, some 25
miles northeast of Eastport, Maine. Calais fronts to the north
and east on the St. Croix River which is a segment of the
International boundary between United States and Canada. The
Calais combined sewer overflow and the effluent from the waste-
water treatment plant discharge into the river. The impact of
the City’s wastewater system has, therefore, come under the
scrutiny of the International Joint Committee Advisory Board on
the St. Croix. In April, 1974, a request was made of the Region
I Operations and Maintenance Section to investigate reported
operational problems at the plant and to report any findings or
recommended remedial actions to the IJC prior to their August
meeting. The request was complied with as follows:
1. An in-house review was made of plant pertinent data,
past 0 & M inspection reports, and the plant’s last
years’ operating records.
2. A field reconnaissance was conducted to evaluate the
reported conditions and to plan any action deemed
necessary.
3. A major technical assistance effort was recommended and
carried out at the joint request of the City and the
State of Maine DEP.
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Calais Wastewater Treatment Plant
The plant was designed to provide treatment through the contact
stabilization mode and was sized to treat an average combined flow
of 0.74 MGD with peak design of 2.1 MGD. The 1995 design P.E.
was estimated at 5,500. The 1970 census indicates a population
of 4,044 which represents a decline of 4.2 percent since 1960.
There is no known industrial waste discharged to the system.
The plant is protected by a combined influent/by-pass structure
just upstream of its headworks, which by-passes all flows over
2.1 MGD. The headworks contain a hydraulically operated influent
gate, a parshall flume, grit removal, and a comminuter with a
bar-rack by-pass. The treatment units consist of three aeration
tanks, two final clarifiers, and a chlorine contact chamber. The
design flow pattern provided two reaeration tanks and one contact
zone. Aeration is provided by two-speed mechanical aerators. The
sludge system provides for return to the reaeration tanks or wasting
to a flotation thickener, then to an aerated sludge holding tank,
and then to a vacuum filter. Dewatered sludge and grit is disposed
of at the City’s landfill. Scum is collected and processed through
the same system as the sludge. See Figure 1 for the flow diagram
and Appendix B for details on pertinent data.
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Plant Operational History
The Calais plant received its Grants Compliance inspection
in September, 1969, and was inspected by the 0 & M Section in
June, 1972, and October, 1973. All inspection forms reported
clean conditions and apparently good maintenance. However, the
operation of the plant was found to be less than desirable,
especially during the June, 1972, visit when the system was
found to be choked with solids and its effluent badly degraded
by solids carry-over.
The review of the plant’s operating records revealed that only
limited efficiency testing was being accomplished, and it was later
learned that the testing was performed on grab samples. BOD testing
was run only six times during the year with results indicating
that removals ranged from 72 to 94 percent. Suspended Solids were
measured 22 times with removals ranging between 11 and 87 percent.
Due to the low frequency of testing, the above data is not considered
to be truly representative of the plant’s efficiency. The records
indicated that MLSS ranged from 2,000 to 14,000 in the reaeration
tanks and from 1,000 to 8,000 in the contact zone. Only 90,000
gallons of sludge had been wasted during the year of record. By-
passing of excessive flow was recorded 40 times during the year
with no incident lasting a full 24 hours. A sumary of plant
historical operating data is contained in Appendix C.
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Field Reconnaissance
The field reconnaissance was conducted by representatives
from EPA Headquarters, EPA Region I 0 & M Section, and the
Maine DEP on May 8 - 9, 1974, and the following conditions
were observed:
1. The effluent from the final clarifiers carried a heavy
concentration of solids washout. The chlorine contact
chamber effluent was highly turbid, but due to its
excessive detention time, most of the suspended solids
settled out before reaching the outfall. This condi-
tion had given the plant a better apparent efficiency
than the process had actually been producing. The
detention time in the contact chamber is about four
hours with the present average daily flow.
2. Weirs throughout the process units were out of level
particularly at the discharge end of the final clarifiers.
The influent distribution ports to the clarifiers cause
short-circuiting and eddies along the sides of the tanks.
3. The chlorine contact chamber had considerable floating
solids and, judging from the gas bubbles, was partially
filled with solids.
4. All equipment was reported to be operable. However, it
was noted that the influent gate malfunctioned when
subjected to high flows.
5. The lack of shelter over the coil filter conveyer belt
was given as the reason for not wasting and dewatering
sludge during inclement or cold weather.
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6. The sampling and testing procedures were found to be
only marginally satisfactory. The testing was being
done on grab samples, and while the lab techniques
appeared to be in line with standard procedures, they
were considered to be somewhat sloppy.
The mode of operation was reviewed and found to be questionable
due to the size of the process units. The aeration tanks provide
detention times of + 2.5 hours each with design flow and about
9.5 hours with the actual average daily flow. Classic design
for contact stabilization calls for detention in the contact
zone of only 30 to 60 minutes. Due to the inherent flexibility
of the process, it was considered advisable to suggest converting
the plant to a plug flow conventional activated sludge process.
This could be accomplished by using the No. 1 reaeration tank and
the contact tank as a comon aeration basin with a detention time
of 5 hours at design flow or + 19 hours with the daily average
flow. The No. 2 reaeration tank could be utilized as an aerobic
digester. The plant was found to be equipped with adequate metering
and pump variability to warrant trying to control the process by
technology being advocated by Mr. Alfred West, Chief, Waste Treat-
ment Branch, NFIC, Cincinnati, Ohio.
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Preparation for Technical Assistance Program
The above observations and the proposed process modifications
were discussed with the City Manager and the plant personnel.
There was a real desire for technical assistance at the plant,
and a formal request was made for such help. Before starting
the technical assistance effort, the City was told that they
must accomplish the following items of work:
1. Solids, throughout the system were to be lowered, to
about 2500 mg/i.
2. Solids in the chlorine contact chamber were to be
removed.
3. All weirs were to be leveled and the influent ports
to the clarifiers modified to even out the flow.
4. The testing program had to be stepped up to include
daily Suspended Solids and BOO twice per week. All
testing was to be done on eight-hour composite samples.
5. Work was to be started on a shelter for the sludge
truck and coil filter conveyor belt.
All of the conditions were agreed to and assurance was given
that there would be funds for any overtime work that might be
required. The State agreed to match all time spent by EPA personnel,
and a schedule was established with a joint effort during the first
week, followed by alternating weekly tours manned first by EPA and
then by the State DEP. The 15th of July was selected as the date
to start the exercise.
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During the month that preceded the resident work, the coil
filter clogged several times and the diaphragm of the lime pump
ruptured, thus delaying the wasting of solids. An attempt was
made to dewater the No. 3 aeration tank and clean out several
feet of settled solids, but this failed due to a malfunction of
the crane being used for the work. These problems made it
impossible for the City to comply with our solids reduction
requirement, and the exercise had to be started with a MLSS
concentration of 3100 mg/i. The testing program was modified
about as we requested, but none of the other work was done.
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Technical Assistance Implementation
On July 15, 1974, the resident phase of the technical assistance
effort was started. The process and operational controls were
modified as follows:
1. The No. 2 reaeration tank was converted to serve as
an aerobic digester.
2. The No. 1 reaeration tank and tank No. 3, the contact
zone, were interconnected to act as a single aeration
tank. Both the influent and the return sludge were
directed to the upstream end of the No. 1 tank.
3. Temporary work was done to modify the inlet ports of
the clarifiers to provide smaller and even-sized
openings. This was done to create an artificial head
which, in turn, would drive an even flow through each
port. Overflow weirs were leveled by eye.
4. Control testing was initiated using settlometers, centri-
fuge, turbidimeter, 0.0. meter, and sludge blanket finder.
A series of tests were run at 0600, 1100, 1500, and 2100
hours each day. Essentially the control testing was
used to regulate the amount of return sludge and to
visually show the condition of the sludge in the system.
The plant personnel provided us with daily pH and
Suspended Solids of MLSS, influent and effluent. Settleable
Solids were measured in the influent and effluent. BOD
continued to be run twice per week.
5. An attempt was made to determine proper wasting routines,
and the sludge drying operation was speeded up.
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Plant Responses
Clarifier Modifications
The plant was found to be sensitive to both the control
measures taken and to a number of unforeseen process interferences.
There was an immediate favorable response to the modification of
the clarifier inlet ports and to the leveling of the overflow
weirs. Visible short-circuiting was eliminated as soon as the
ports were modified to be of equal width and their vertical
dimension was reduced sufficiently to cause an artificial head
In the inlet channel. The work done here warrants the instal—
lation of permanent slide gates. Until such gates are installed,
scum will collect’ in the channel and create a nuisance maintenance
problem. The weir plates on the overflow launder were adjusted
by eye to even out the flow from the clarifiers. This was
effective in reducing the pumping of solids from the tanks.
This condition is comon to all rectangular tanks where the
launder is located too close to the discharge end. The weirs
should be leveled by a surveyor and be locked in place if
possible.
Return S1udge Pumping Control Measures
There was a rapid response to the reduction of the return
sludge pumping rates. Return rates had been maintained at about
600 gpm, which represented a return of about 400 percent during
the daytime hours and 800 percent at night. New rates were
calculated, and the pumps were slowed to their minimum speed.
However, more rate reduction was needed, and an attempt was
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made to run the system with only one pump drawing from both
clarifiers. This operation approached the calculated return
rates, but coning occurred in one tank, and the other tank
clogged and filled with solids. By the time this Ias discovered,
the solids had become septic and their return caused a plant
upset. A second and more successful attempt to control pump
rates was accomplished by manually switching the pumps On and
off at regular intervals during the working hours. •.The effort
had positive results, and a recomendation was made to install
timers on the pumps so that proper return rates can be maintained
day and night.
Chemical Interferences
The treatment process was subjected to major upsets every
time sludge was wasted. The chemicals associated with sludge
conditioning were discharged to the headworks with the effluent
from the thickener and the filtrate from the coil filter. Decant
from the sludge holding tank was also returned to the system and
was often ina septic condition. The combination of by-products’
from the sludge dewatering units raised the pH in the ‘aeration
tanks to toxic, limits and killed most of the microorganisms in
the system. Lime compounded the problem by causing a colloidal
haze that-would not settle out in the clarifiers. The daily
quantities of sludge dewatered often reached 20,000 gallons,
and the liquid’return amounted to 10 to 20 percent of the total
influent to the plant. It was not until the last day or so of
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the resident phase that it was discovered that the lime feed
pump had been stepped up without any compensation in the ferric
chloride feed system. Corrections were made to both feed systems
and the resulting effect was a near neutral pH discharge back
to the treatment process. The elimination of this problem has
had a marked effect on plant efficiency.
Mechanical Aerator Operation
Another feature of the plant found to be adversely affecting
efficiency was the use of two-speed mechanical aerators. During
daytime hours high-speed was satisfactory, but at night high-speed
aeration would over-oxidize the sludge. Low-speed operation would
reduce the nighttime D.O. level, but the units would not impart
sufficient energy to keep the solids properly suspended. Timers
should be installed on the aerators so that D.O. can be maintained
day and night without subjecting the units to improper mixing
due to slow speed operation.
Outside Interferences
Treatment efficiency was lowered by a number of factors
outside of the plant. Storm surges would be felt in a matter
of minutes, and solids would wash out. However, the washouts
that did occur were minor with respect to those that were observed
prior to the conversion of the plant to the new controls. Power
losses at night resulted in the loss of aeration and pumping
capability. While an emergency generator would take over during
the outage, all of the electrical units required re-setting
before they would come back on commercial power. This meant
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a number of nighttime hours of operation where sludge would
tollect in clarifiers and turn septic. The dumping of septage
was found to have minor effect on the process during the resident
phase. The practice of dumping septage at a location remote
from the plant shou Id be continued.
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Evaluation of Program
Hi stori cal Background
The technical assistance effort was conducted in two phases,
first with EPA and State personnel in residence and then with
plant personnel running the facility, under daily supervision
by phone. The measurement of the overall improvement gained
through the changeover from contact stabilization to conventional
activated sludge is quite visible but is rather difficult to
calculate. With lower solids in the system, the color of the
MLSS improved. The foam on the aeration tanks decreased and
turned nearly white. The clarifier contents cleared enough to
see several feet below the surface and solids washout nearly
ceased. The most remarkable change was the disappearance of the
plume that was once so visible in the St. Croix River. However,
the true evaluation of improvement must be measured by increased
efficiency. As stated earlier, the historical record of the
plant’s efficiency must be based on 6 BOD and 22 Suspended Solids
tests. Further, all test results were made on single grab samples.
Due to the number of BOD tests, no attempt was made to evaluate
efficiency through their results. The Suspended Solids data
was compiled, and it was found that the plant was operating at
about a 67 percent efficiency with respect to solids removal.
Phase I
The efficiency attained during the total technical assistance
program must be considered in two phases due to complications
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caused by process changeover and chemical upsets that occurred
during the resident phase. Efficiency during the first phase
is based on 19 Suspended Solids and 10 BOO tests. Tests were
made on six-hour composite samples. The accuracy of the solids
tests is suspect due to known problems caused by a ma1functionin
Mettler balance. However, a correlation was made between turbidity
and suspended solids by the NEIWWI van when that unit visited
Calais. The results of the BOO tests were erratic in that
computed removals did not approach those that were obtained with
Suspended Solids. The removals should have been similar since
the waste being treated was domestic waste with no industrial
interferences. For example, on August 14, the effluent Suspended
Solids were 4 mg/l, the turbidity was about 2 JTU, and the BOO
was reported as 50 mg/i.
The BOD removals during the resident phase indicated a rather
poor 60 percent efficiency. Unfortunately, there were no BOO
tests run during September so this measure of efficiency cannot
be used to show any improvement in plant operation. The first
phase Suspended Solids tests indicated an average effluent
concentration of 38 mg/i which represented a 79 percent removal
efficiency.
Phase II
There was a marked improvement in plant efficiency during
the second phase of the exercise due to the elimination of
chemical upsets. The Suspended Solids concentrations in the
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effluent averaged out at 15 mg/i and were 10 or less eighteen
of the twenty-six days. The results of the total exercise are
shown in Figure 2.
The changeover in the mode of operation is considered to be
successful. The plant personnel have a good grasp of the new
mode and have been able to run the plant well within permit
limitations for over one month. They must continue with the
control testing program established and must follow the dictates
of the plant itself. As conditions change, for instance as cold
weather approaches, the operating parameters will change. There
are no magic numbers that can be given by which to run the process.
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Recommendations
There were a number of deficiencies that need correcting
before the plant can reach its full efficiency. The following
modifications are considered as being necessary for continued
good operation:
1. The return sludge pumps are designed to operate between
125 and 550 gpm. Since the influent flow rates were
found to range around 0.100 MGD at night and 0.300 MGD
during the day, the pumps should either be modified or
be equipped with timers so that they can be set to match
some fraction of the influent flow. They are currently
returning about 100 percent of the daytime flow and about
300 percent of the nighttime flow.
2. The plant is equipped with two-speed mechanical aerators
which develop excessive D.0. during periods of low flow.
These units should have automatic timers so that they can
be set to run on a timed cycle.
3. The final clarifiers are in need of repair and modification.
The overflow weirs must be leveled and the flights replaced.
The inlet ports must be choked down to a uniform width and
slide gates installed to control the flow.
4. All flow meters must be kept in repair and well calibrated.
5. A shelter must be provided to protect the loading area for
dried filter cake. Early construction is needed to correct
this problem since inclement weather and freezing tempera-
tures interfere with the solids handling operation.
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6. The stop-logs in the stornwiater overflow structure
leak and allow a backflow of salt water to enter the
plant during high tides. This condition must be
corrected.
7. The hydraulically operated influent gate must be
adjusted. The gate mechanism causes the unit to
oscillate when it senses high flow. This condition
is causing undue wear and tear on the unit and its
related meters.
8. The chlorine contact chamber is too large for any flows
received at the plant. Even with the maximum flowof
2.1 MGD, the detention time is 24 minutes. Consideration
should be given to modifying the structure to provide
two parallel chambers which could be operated separately.
9. The most severe upsets that were observed resulted due
to the discharge of poor filtrate from the vacuum filter.
The filter, the feed pumps, and the vacuum pumps are all
in need of cleaning. A regular maintenance program must
be started. Consideration should be given to converting
the system to polymers for sludge conditioning.
10. The laboratory procedures were found to be highly suspect.
The best data for measuring plant efficiency came from
turbidity readings which were correlated to Suspended
Solids that were measured by qualified lab people. A
major problem in the lab is a highly inaccurate Mettler
balance. This unit should be repaired, calibrated, and
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positioned in a fixed place in the lab. Consideration
should be given to more lab training. Both operators
should be qualified to perform all tests.
11. Old settled solids in the aeration tanks and the chlorine
contact chamber must be removed and not allowed to
accumulate again.
12. A better alarm system should be installed to insure that
someone is warned when a power outage has shut off pumps
or aerators. These units must be reset by hand. Loss
of power and the lack of someone to restart pumps was a
major cause of plant upsets during our stay.
13. Wasting sludge to the aerobic digester must be done on
a fill and draw operation. Supernatant and digested
solids overflowing from the digester will cause plant
upsets which will, in turn, degrade the effluent.
14. A better routine is needed for scum removal. Too much
scum is allowed to accumulate. This increases the
maintenance and cleaning problems.
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Conclusion
The technical assistance program concluded on September 24,
1974. However, plant personnel have agreed to continue sending
in weekly reports of their control testing. These reports will
be closely watched to ensure that the system is operating
properly. The results of cold weather operation will be of
value in any other technical assistance effort undertaken by
the 0 & M Section.
The improved plant efficiency achieved through the technical
assistance program will reduce the amount of pollutants being
discharged to the St. Croix River. There is still the problem
of stormwater overflows from the City’s combined sewer system
that must be corrected before the goal of complete pollution
abatement will be realized.
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Photo Captions
1. Final clarifier effluent weirs - Weir plates in both
clarifiers are adjustable and often become disturbed during
cleaning operations. Uneven weir plates create flow currents
that cause the loss of solids through pumping action. Scum
that accumulates ahead of the weirs should be removed more
frequently to reduce unsightliness and to ease cleaning
problems.
2. Final clarifier inlet ports — Multisized ports cause
short-circuiting and eddies along the clarifier sides.
Ports should be made equal width. Slide gates should
be installed to control flow.
3. Flotation thickener - Inefficient operation and improper
chemical dosage will result in the discharge of supernatant
which would contribute to process upsets.
4. Coil filter - Excessive use of lime during sludge condi-
tioning causes high pH values in the aeration tanks.
Filtrate returned to the system often reaches volumes
approaching 10 to 20 percent of the flow.
5. Sludge loading area - Dewatered sludge is conveyed from
the control building to an open truck exposed to the
weather. Freezing temperatures and inclement conditions
are a deterent to the dewatering operation. A shelter
is needed to protect the truck during loading operations.
6. Influent gate - Due to maladjustment of hydraulic controls,
the gate oscillates when high water is sensed. This action
causes undue wear and tear on the unit and on its related
meters.
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k ..
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A
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Appendices
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Appendix A
The sumary of historical operating data was compiled from
the monthly reports submitted to the Maine DEP. The removals
indicated are considered to be highly questionable since they
were based on a testing program run on single grab samples.
The Suspended Solids values were used in an attempt to
establish plant efficiency background, but BOD values were
discarded due to the very limited number of test results.
Figure A-i represents the reported MLSS concentrations
recorded on the monthly operating reports submitted from
March, 1973, to March, 1974. The graph indicates the con-
ditions that existed during the contact stabilization mode
of operation, the transition between modes, and the condi-
tions that now exist under the plug flow conventional
activated sludge mode.
A-i
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Suniiiary of Historical Operating Data
Flow (MGD)
S.V.I.
BOO (mg/I)
SS (mg/i)
aste Sludge
Month
Daily Peak Mm
Avg High Low
Inf Eff # Tests
Inf Eff # Tests
(Gais)
1973
March
April
May
June
f&) July
August
Sept.
Oct.
Nov.
Dec.
1974
Jan.
Feb.
March
.634
1.157
0.153
.728
1.8
0.463
.459
1.57
0.266
.235
.6 19
1.26
.175
.512
.100
.291
.842
.092
-
.472
-
-
. 586
-
.493
1.68
0.15
.92
1.61
.265
-
.808
-
.32
1.05
0.05
1.0
1.07
.229
85 15
64 4
1
1
46 56 26
64 86 43
57 71 41
64 81 28
65 82 52
47 55 41
50 62 43
57 89 45
53 90 41
37 47 33
44 54 36
57 50 66
57 48 61
N. V.
58
21
2
28
25
1
94
21
3
177
23
3
87
18
3
226
62
2
-
45
35
2
.
60
37
2
51
15
4
15,832
10,702
19,139
21 ,185
23, 89
118
24
1
209
30
2
100
28
1
Note: BOO and SS data based upon grab samples only.
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Volume
Size cu.ft../aal
1/4” X 1 1/2”
@ 3 1/2” O.C.
Detention Time-Hours
Avg
Flow Design Peak
.200ma .740ma 2.lma
Unit
Appendix B
Pertinent Data
Inf 1 uent/Bypass Chamber
Sluice Gate
‘ Parshall Flume
Grit Chamber w/Hydrogritter
Commi nuter
Bar Rack
Bypass @ 2.1MGD
14”
5’ X 2’
Raw
Sewage Pumps (2)
No. 1 Aeration Tank
30 X 30 X 11
10,350/77,625
9.3
2.5
No. 3 Aeration Tank
31 X 30 X 11
10,885/81,418
9.8
2.6
Final Clarifiers (2)
585
X 12
X 75
10,530/78,764
9.4
2.5
Condi tion-Remarks
Poor; stop-logs leak
at high tide
Oscillates w/high flow
Satisfactory
Satisfactory
Variable speed w/flow
Matcher control
.9 Satisfactory. Two—
speed mech. aerator
.93 Contact switch worn
.9 1) Unequal flow
distribution
2) Badly worn flights
3) Effluent weirs not
level
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Unit
Chlorine Contact Tank
Chiorinators (2)
Aerobic Digester
Floatation Thickener
Thickener Feed Pump
Vacuum Filter
FeC1 3 S01. Tank
Lime Tank
Polymer Tank
Sludge Storage Tank
Filter Feed Pump
Compressor Pumps (2)
Return Sludge Pumps
Influent and Return Sludge
Meters
Size
30 X 27, 8 X 6
0-200 lbs.
30 X 30 X 11
50 sf
60 Sf
16 X 15.3 X 7.75
125-500 GPM
Volume
cu.ft./gal
4,457/33,338
10,350/77,625
150 gal.
250 gal.
Detention Time—Hours
Avg
Flow Design Peak
. 200mg .740mg 2.1mg
4 1.1 .4
Condi ti on-Remarks
1) Contact time too long
2) Solids in bottom of tank
Post and pre-chiorination
Baffle needed to limit
short-cl rcui ti ng
Sati sfactory
Sati sfactory
Needs cleaning and
maintenance
Sati sfactory
Satisfactory
For thickener
Poor air distribution
Satisfactory
Satisfactory
1) Cannot pump at low
enough rate
2) One pump will not
pull from both tanks
Satisfactory
-------
Detention Time-Hours
Avg
Volume Flow Design Peak
Unit Size cu.ft./gal .200mg .740mg 2.1mg Condition-Remarks
Motor Control Unit 1) Weak contacts
2) Return pumps on
manual reset
3) Poor alarm system
Generator Satisfactory; runs
entire plant
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Appendix C
Figures C-i and C-2 represent the operational variables
that were used to control the facility during the technical
assistance program. Similar charts are plotted and maintained
at the treatment plant. However, the charts at the plant are
plotted showing each individual test. The average daily charts
presented herein contain straight-line interpolation of data
between points where no data was generated. The seven—day
running averages are included to show trends that occurred
during the exercise. The parameters that are depicted are
as follows:
SSV - Settled Sludge Volume. The separate lines represent
the settled volume at Time = to 5 mm., 30 mm., and
60 mm. The readings were obtained using a Mallory
Setti ometer.
SSC - Settled Sludge Concentration (percent by centrifuge).
The ssc = 1000XATC
SSv
ATC = Aeration Tank Concentration (percent by centrifuge).
The separate lines represent the concentration of the
settled sludge at Time = 0 = ATC, 30 mm., and 60 mm.
WCR - Weight to Concentration Ratio (MLTSS/ATC)
MLTSS = Mixed Liquor Total Suspended Solids mg/i.
Turbidity determinations were made using a HACH Model 2100A
Turbi dimeter.
The daily log contains the chronological order of happenings
during the technical assistance exercise.
C—i
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PAGE NOT
AVAILABLE
DIGITALLY
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Daily Log
July 14, 1974 - August 9, 1974
Date/Time
Action/Condi tion
Effect/Remarks
7-14/1900
l.A. team arrived, unloaded
equipment & toured plant
Flow = 0.150 MGD
RSF = 500 gpm = ± 0.710 mgd
Effluent looked good
Met with operator and
inspected plant
F1ow = 0.300 MGD;
to 220 gpm
1030 Ran first control test;
RSF reduced to 190 gpm
1130 State 0 & M arrived; showed
“West” slide series
Half-hour heavy shower
Ran contro1 test
Clarifiers unbalanced with
outer ports closed
Charts indicate extreme
low flow from 2300 to
0700 hours
Fast settling old sludge
with clear supernatant
Effluent turbidity = 6 JTU
Impossible to slow RSF to
calculated valve
Fast settling sludge
Turbidity = 4 JTU
ATC balanced at 4%
MLSS = 3100 mg/l
Solids in digester =
10,000 mg/l
7-16/0615
1030
1300
1330
2130
Ran control test on low
flow condition
Ran control test
Shut off and settled
digester for 30 mm.
Wasted 50 gpm for 20 mm.
Filtered sludge and cleaned
out holding tank
Leveled discharge launder and
adjusted inlet ports of
clarifiers. Ports made equal
and small enough to cause
artificial head
Ran control test. Put #2
aerator on low. Replaced
belt on #2 sludge pump and
reduced rate to 150 gpm
Better settling characteristics
Turbidity = 2 JTU
RSC = 7% due to return rate
of 190 gpm vs. flow of
0.100 MGD night flow
Improved test results
Turbidity = 10 JTU due to
unbalanced flow in clarifiers
Flow pattern leveled off
and solids washout lessened
greatly
Turbidity = 2.9 JTU
0.0. in #2 aeration tank =
4.2
RSC less than 10%
7-15/0700
0730
RSF reduced
1630
1800
C-2
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Action/Condition
Effect/Remarks
Date/Ti me
7-17/0600
0800
1030
1630
2130
Ran control test
Filtered sludge 8 hours
Ran control test
Ran control test
Ran control test
System lost solids all day
Last two control tests had
very low ATC and RSC
Very rapid SSV; 2” sludge
blanket
0900 Coning developed in
#1 clarifier; solids
filled #2 clarifier
#1 clarifier
mm. @ 160 gpm
1030 Started both sludge pumps
@ 350 gpm
Set both pumps to slowest
speed
Ran control test
Ran control test; valve on
#1 clarifier not opened and
tank filled with solids
DOB = 4 to 5 in.; ran pumps
@ 300 gpm for 1 hr. and then
set to low speed for rest of
night
ATC less than 2%; apid
settling; RSC about 4%
Return sludge rate dropped
to 80 9pm; return mostly
water; no blanket in #1
clarifier
NOTE: Loss of solids in
return misinterpreted.
Thought filtrate from
dewatering 20,000g of
sludge caused solids to
drop in aeration tank.
Solids build-up in clarifier
not discovered due to
malfUnction of blanket finder
TSU = 0.620
Wasted 0.O92XSU or 16%
of system; blank9t dropped
from + 7’ to 0.5’ in 1 hr.
Distributed solids through
system; developed 4 to 6
in. blanket in both tanks
Better settling characteristics
Turbidity = 3 JTU
Mechanical error upset
system and invalidated
control test
7-19/0630
Set return pumps @
and ran 15 mm. on
off for avg of 100
Changed to #2 pump
@ 200 gpm
200 gpm
— 15 mm.
gpm
only
Use of single pump caused
coning in #1 tank
7-18/0630
Ran control test
0950
Shut down
Wasted 12
XSC = 46%
1540
1600
2130
C-3
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Date/Time
Action/Conditions
Effect/Remarks
0900
0930
1030
1100
1630
2000
Heavy rain increased flow
to 1.25 MGD
Power failure
Set both sludge pumps @
150 gpm for total of 300 gpm
with 40 mm. on and 20 mm.
off. Shut #2 aerator off
1 1/2 hours
Closed #3 aeration tank
#3 aerator back in service
Aerated tank 40 mm. and
then set up normal flow
pattern; started wasting
4500 gal. @ 19%
Stopped intermittent pump
operation
Ran control test
Turbidity 100 JTU
Solids washout due to high
f1ow; automatic bypass
activated
Turbidity droped to 20 JTU
after initial surge; solids
washout never got as bad as
normal conditions before
exercise
Emergency generator started
Lost #3 aerator
About impossible to run pumps
without coning; intermittent
operation gives better flow
control; timers seem to be
warranted
7-20/0900
0910
1010
1700
Ran control test
Ran pump tests @ 200 gpm,
20 mm. on - 20 mm. off
Wasted 3300 gal @ 17%
Set both pumps @ 150 gpm
AFI = 0.250
Ran control test
Wasted 1500 gal.
ATC = 4.9%; SSV 5 510
Heavy rain all night
0910 with #2 on DOB #1 = 1/2”
DOB #2 = 1 1/2”
0930 with #1 on same blankets
0950 with both off same blankets
Very little change
Digester short-circuits to system
7-21 / 1000
1400
Ran control test; set
aerators to low speed
Ran control test
Limited wasting
AFI = 0.100; SSVç 530
D.0. #1 = 5.6, #2 = 8.4
Mixers mix poorly at low speed
Old sludge settling too fast
Digester short-circuiting
Alt = 4.25; assumed that old
bottom solids adversely affecting
new sludge
0700
ATC Tank #1 = 4%; Tank #2
SSV 5 under 500; turbidity
Heavy rain continued
= 5%
fa i r
C-4
-------
Effect/Remarks
Date/TI me
Action/Conditions
7-22/0800
1000
1330
2100
Ran control test
Wasted 4500 gal @ 15%
Wasted 3400 gal @ 16%
and 1500 gal @ 15%
Two septic tank trucks
dumped
Ran control test
ATC = 4.5; settling better
MLSS still too high
Wasted 16% of TSU but WCR
remained over 1000; MLSS
over 4000; SSV 5 less than
600; sludge grey in color;
Wasting reduced ATC to 4%
Plant seems to need ATC
+ 3.5 and MLSS = + 3000
Pbor settling; moFe wasting
needed
Ran sludge thickener a11 day
to make room fOr wasting.
Found 2—3’ of solids in ci
contact chamber; tide gate
leak during high tides and
allow seawater to enter system
7—23/0700
0900
1500
2100
Power lost from 0400 to 0700
Ran control test
Ran dilution tests
Ran control test
#3 aerator out of service
No control test
Adversely affected sludge age
ATC = + 4.0; MLSS = + 3200
A dilution test was Fun to
measure effect of thickener
effluent and filtrate. The
total of each amounted to
12,000 gals. with a flow
of only 0.189. Using 100 ml
dilution, there was a 5%
increase in settling. The
filtrate drops the pH to
less than 6. Biological
activity is about 0. 24 hours
needed to assimilate sludge
processing chemicals. Back to
back wasting days not advisable
SSV = 300; poor settling
probably due to chemicals
in filtrate; better settling
in a.m. pH dropped to 5.9
Aerator off 4 hours; power
outages due to line work
Outage starts a 3 a.m.
Pumps are on manual reset and
will not start when power is
restored. Aerator switch
malfunctions. The loss of
power and aerator down-time aging
already old sludge.
7-24/0700
Power out 0400
Sludge pumps &
aerator out
to 0700
#3
Blanket up to 6”; bad solids
washout; septic sludge being
filtered
C- 5
-------
Date/Time
Action/Conditions
Effect/Remarks
1100
Ran control test
SSV 5 = 385; very old sludge
due to mechanical problems
7-25/a.m.
1430
1500
1600
2100
Ran filter & thickener
all day; sludge over-
limed
Effluent degraded
Ran control test
Added acid to effluent
sample
Ran control test
Ran control test
Excess lime caused haze
throughout system
ATC = 3.0 after wasting 6000 gal.
Rapid settling due to chemicals
Solids lowered
Haze precipated out
MLSS = 3000; ATC = 3.0
Poor settling; cloudy clarifiers
Very low flow
MLSS 3000; ATC = 3.0
SSV 5 = 200; no biological
indicators;
Turbidity = 70 JTU
7-26/0700
7-27
1500
1045
Ran control test
Coil filter down for
mai ntenance
Wasted 3000 gal @ 15%
No wasting; 600 gal
septage put in system;
50 gal of muriatic acid
dumped
Ran control test
Sludge pumps on 10 mm.,
off 20 mm.
System recovering; some life
in sludge; haze lessening;
Sludge holding tank has diffuser
that has never been cleaned;
Coil filter should be cleaned
Coil bathed in muriatic acid
for 24 hours; heavy scum buildup
upstream of clarifiers; scum
well drawn down & thickened;
2000 gal. drawn from digester
MLSS 3912; WCR = 978
Biological indicators returning
WCR = 942; ATC = 4
No room in digester to waste
Bad scum problem; good indicators
7-28
2030
Ran control test
Ran control test
Excellent effluent; no floc
0.0. meter out of calibration
MLSS = 3824; XSF = 0; ATC = 5.0
C-6
-------
Action/Conditions
Effect/Remarks
Date/Time
7-29/0800
1500
2100
Ran control test
Wasted 2850 gal @ 17.5%
Solids to digester
(501 XSU)
Started to thicken and
fi 1 ter
Waste sludge from digester
Shut down filter
Ran control test
Ran control test
Few solids in effluent; good
foam on both aeration tanks
ATC = 5.55
Turbidity = 3.0
Filtrate heavy with solids,
acid bath of filter appeared
to have little effect on
performance
Influent flow meter out
Wasted 4000 gal from digester
ATC = 5.3; MLSS = 4852 mg/l
WCR 765; Turbidity = 3.0
Settling good
ATC = 5.5; Turbidity = 2.5
WCR = 890; MLSS = 4896
Settling good
Ran control test
Wasted 2100 gal @ 16%
to digester (336 XSU)
Filtering sludge
Wasted 3300 gal @ 22%
to digester (726 XSIJ)
Ran control test
2000 Ran control test
Filtered sludge all day
Wasted sludge to digester
2800 gal @ 15.6% (436 XSU)
Wasted sludge to digester
3000 gal @ 19% (570 XSU)
Ran control test
Wasted 3000 gal to digester
Tested Mettler balance
Effluent fair; some straggler
floc, heavy at times
ATC = 5.5; Turbidity = 6
Settling fairly fast
SSV 5 = 520
ATC = 5.0; Turbidity = 20
Settling still rapid
Evidence of lime from filtrate
in system; effluent cloudy,
almost milky; MLSS = 4898
WCR = 980
ATC = 5.3; Turbidity = 3.2
Settling fair; SSV 5 = 690
Instrument read; .0114 mg low
when weighing a 147.5 g weight
and .0083 mg low when checking
the initial and final weight
of a filter paper blank run
with distilled water
7-30/0800
0900
1200
1500
Turbidity = 1.7; ATC = 5.7
Settling good
7-31/0800 Ran control test
0830
1330
1500
ATC = 6.0; Turbidity = 3.5
Settling much slower
SSV 5 = 790; some rain last night
C- 7
-------
Date/Time
Action/Condition
Effect/Remarks
Examination of air system
to sludge holding tank
Scum problem upstream
of clarifier
6000 gal wasted to
holding tank
Sludge pumps set 15 mm.
on and 15 mm. off
1500 gal of supernatant
from holding tank returned
to system
Tested Mettler balance
2100 Ran control test
Wasted 2126 gal @ 21%
8-2/0700 Ran control test
8-5/0700 #2 pump lost bearing night
of 8-2; both clarifiers
left in operation
Closed #1 tank and used
#1 pump on #2 tank
Started coil filter
No blocked lines; valves
only served one manifold at
a time; valves were modified
to feed both manifolds; air
regulator was found to malfunction
Must be hosed down every day
until gates are provided
Coil filter not used in effort
to keep lime out of system;
heavy rain helped to purge
system of high pH; pH dropped
to + 6.5
ATC= 5.7; Turbidity = 7.0 JTU
SSV 5 = 790; settling good
18” blanket of sludge in both
clarifiers; all sludge returned
to system; w/RSC = 45%
SSV = 300; ATC = 4.0
ATC = 5.5; SSV = 750; loss of
return for 8-9 hours did not
seem to cause major upset;
dark brown sludge with good
floc; some solids washout
Info, requested from pump
company re timers
Suggestion made to use less
lime and allow wetter cake
drift with small weights
error with large weights
4064; color dark and
dark foam; more wasting
MLSS = 5500
Coning occurred in #1 tank
#2 tank filled with 6’ of
solids; no room in digester;
Sludge septic and black
Returned solids to aerators
8” blanket established and
maintained
Added 735 lbs. of lime in
4 hrs; pH = 8.5 in both
aeration tanks
2000 Ran control test
8-1/0640 Sludge pumps off 8 to 9
hours - ran control test
1100 Ran control test
Large
Minor
MLSS =
muddy
needed
C-8
-------
Action/Condition
Effect/Remarks
Date/Ti me
Lost air compressor
Scum buildup at clarifier
inlets
NEIWWI van arrived
Running both clarifiers
with #1 pump
1200 Turbidity vs. suspended
solids correlated by NEIWWI
Returned to one clarifier
for night operation
Started both clarifiers
with #1 pump
Wasted sludge, thickened
and filtered
Sampled effluent hourly and
ran SS test with weighing
on NEIWWI scale
Aerators set to slow speed
Cut back to one clarifier
Ran control test
Turned aerators to low
speed till 2300
Ran control test
Started both clarifiers
pH dropped to 7.4; cloudy
clarifier due to lime
precipitate; Turbidity = 63 JTU
initially but dropped to
23 JTU by 0900
Start 3-day lab course that
had been scheduled prior to
our TA program
Major upsets starting to
recover; ATC = 4.2; SSV 6 = 510
Turbidity dropped from 30+ JTU
to 18 JTU
SSV 5 = 750; ATC = 5.25
Clearer supernatant in
settlometer; Turbidity = 12 JTU
MLSS = 4000
Effluent improving; unable to
waste due to lack of space in
digester
MLSS = 4800; effluent SS less
than 20 all day
Effluent clouded by lime
Stopped filter when pH reached
8.0; sludge rose in settlometer
in 80 mm. due to over oxidation
Turbidity and SS checked for
correlation
0.0. too high; slow speed
causes poor mixing; problem
starting #3 aerator
Rise time + 45 mm.
0.0. very high; set aerators
low at night and high during
days..
Good tests; system seems to be
recovering
Shut off filter for 2 hrs
0900
2000
8-6/0700
1045
Ran control test
Ran control test
1600
8-7/0700
1600
2100
8-8/0700
0730
1100
Ran control test
C—9
-------
Date/Time Action/Condition Effect/Remarks
Ran thickener and coil Stopped filter at 1200 for
filter all day short time since pH reached
8.3; ran high pH M.L. from
#1 aerator to final tanks
to purge system; worked OK
1400 Ran control test Cloudy precipate; Turbidity =
12; colloidal suspension caused
by lime
1600 Cut back to one clarifier Poor mixing with aerators on
Cut aerators for short low
period and then ran on low
8-9/0700 Changed rate of lime Operator had doubled lime
FeCl 3 feed dosage with no compensation
in FeC1 3 feed; FeC1 3 feed
stepped up from 2.5 to 5.5
and cut lime feed to 3.5
Cake best since we enterd
plant; resulting pH not
affecting plant; Turbidity
dropped to 5 JTU
0900 Reduced lime dosage pH = 6.6
1000 pH = 6.85; good cake
1100 Ran test pH = 6.4; Turbidity = 5 JTU
NOTE: 8-7 discovered that
plant was prechiorinating
influent for unknown period
1300 Ran test pH = 6.6
END OF RESIDENT PHASE
C-i 0
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Appendix D
Calais, Maine, Staffing Requirements
The recommended staffing for the Calais WWTP is based on
the guidelines contained In EPA’s publication “Estimating
Staffing for Municipal Wastewater Treatment Facilities”.
This staffing recommendation is a guide for the City to use
in its determination of manpower requirements. The estimate
reflects geographical location, physical condition, type of
units, and estimated man—hours Involved with each process.
All clerical and supervisory work is included, but maintenance
of the collection system is not considered. The plant should
be staffed by two and a fraction full-time employees. It is,
therefore, recommended that a staff of three people be retained
to rin the facility and to continue with the operation and
maintenance of the pumping stations. This recommendation is
based on the assumption that the plant will be operated seven
days a week but with a reduced staff on weekends.
The following is a breakdown of man-hours per year required
to operate this treatment plant. The manpower need is predicated
on a forty-hour week and a forty-six week workyear.
Work Classification Estimated Annual Manhours
Supervisory 400
Clerical 50
Operation 2,000
Laboratory 500
Maintenance 1,900
Yardwork 400
TOTAL 5,250 hours
D- 1
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